Have you tried a veterinary dermatologist? This doesn't sound like staph to me. Until you find out what you're dealing with, it's going to be very hard to treat. If it's a yeast infection or something autoimmune related, you may make things worse by treating it as a staph infection...
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."